Focus-Shift Check/Adjustment; Spherical Aberration)) - Sony SAL24105 Service Manual

Ver 1.3 2007.07
4-7. FOCUS-SHIFT CHECK/ADJUSTMENT (APERTURE (AMOUNT OF SPHERICAL
ABERRATION))
This section describes the check/adjustment of focus-shift amount resulting change of focal-length by aperture setting.
Equipment
• 1000 mm Collimator
• Flange Back Tester
• A-mount Attachment
• Flange Back Gauge (43.50mm)
• Aberration measuring cap 62mm (SAL24105)
1. Preparations
1) Perform "1. Preparations" of "4-4-1. Flange Back (f'F) Check".
2) Set the checking lens focus to the infinite.
3) Set the focal length 105mm.
2. Checking Method
1) Set the lens aperture to the open aperture position, and measure the flange back (f'F).
2) Set the aberration measuring cap 62mm (F8 equivalent) on the tip of lens as shown in the Fig.4-7-1, then measure the flange back
(f'F).
3) Calculate amount of focus-shift using the following formula, and check that the specification is satisfied.
Note:
The focus-shift amount of the checking lens is difference between the flange back (f'F) of open aperture and flange back
(f'F) reading (using aberration measuring cap 62mm).
Focus-shift = Flange back (f'F) reading (using aberration measuring cap 62mm) - flange back (f'F) of open aperture reading
Specification
Focus-shift (mm) = – 0.11mm to +0.13mm
SAL24105 (3.5-4.5/24-105) (24-105mm F3.5-4.5)
Aberration measuring cap 62mm (SAL24105)
Fig.4-7-1
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